Recent evidence indicates that the ETC complexes are organized into SCs, which increase efficiency of the ETC and reduce oxidative damage.29,30 Impaired assembly of SCs is associated with heart failure.31 Here, we observed reduced assembly of SCs, reduced activity of all the complexes (or their SCs), and increased ROS production in mitochondria isolated from CM-Pcsk9−/− mouse hearts. The gene discussed is PCSK9; the disease is heart failure.